The use of threaded tubular connections for joining flow conduits in an end-to-end relationship to form a continuous flow path for transporting fluid under pressure is well known. Oilfield tubular goods all use threaded connections for connecting adjacent sections of conduit or pipe. Examples of such threaded end connections designed for use on oilfield tubular goods are disclosed in U.S. Pat. Nos. 2,239,942; 2,992,019; 3,359,013; RE 30,647; and RE 34,467, all of which are assigned to the assignee of the present invention.
Prior art wedge thread designs offer distinct advantages over other thread designs which include high torsion, high compression, and reliable internal and external pressure sealing capabilities. There are, however, a few issues that require extreme care when designing connection using wedge thread technology. A first issue is designing connections using metal-to-metal sealing interfaces in conjunction with wedge thread technology. A second issue is the inherent wear characteristics encountered during multiple make and breaks associated with wedge thread technology. The primary problem encountered when trying to incorporate a wedge thread with a conical metal-to-metal seal in the prior art is that a very shallow seal angle is required to compensate for the linear variability of the wedge thread torque stop. This invention incorporates a positive stop torque shoulder in conjunction with the wedge thread, which allows for better axial control of the connection at final make up without sacrificing existing advantages of the wedge thread technology. This better controlled axial location of the connection allows for a steeper metal-to-metal seal angle, thus enhancing characteristics of sealability and galling resistance. The second problem encountered using wedge thread technology is determining when the wedge thread begins to wear to a point that the connection is no longer serviceable as a result of repeated make and breaks. By incorporating a secondary positive stop torque shoulder within the primary wedge thread torque stop configuration, connection wear limitations can be better controlled.